Provide mutable members of UrlRequestContext via pure-virtual interface. Create a pure-virtual interface called HttpUserAgentSettings that provides access to the Accept-Language, Accept-Charset, and User-Agent HTTP headers. Each UrlRequestContext should have a HttpUserAgentSettings implementation attached via set_http_user_agent_settings().

BUG=146596

Review URL: https://chromiumcodereview.appspot.com/10918279

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@166425 0039d316-1c4b-4281-b951-d872f2087c98

43 files changed, 581 insertions, 351 deletions

diff --git a/android_webview/browser/net/aw_url_request_context_getter.cc b/android_webview/browser/net/aw_url_request_context_getter.cc
index 8fbe53c..9b51826 100644
--- a/android_webview/browser/net/aw_url_request_context_getter.cc
+++ b/android_webview/browser/net/aw_url_request_context_getter.cc
@@ -84,6 +84,13 @@ void AwURLRequestContextGetter::Init() {
   builder.set_network_delegate(new AwNetworkDelegate());
   builder.set_ftp_enabled(false);  // Android WebView does not support ftp yet.
   builder.set_proxy_config_service(proxy_config_service_.release());
+  builder.set_accept_language(net::HttpUtil::GenerateAcceptLanguageHeader(
+      content::GetContentClient()->browser()->GetAcceptLangs(
+          browser_context_)));
+
+  // TODO(boliu): Values from chrome/app/resources/locale_settings_en-GB.xtb
+  builder.set_accept_charset(
+      net::HttpUtil::GenerateAcceptCharsetHeader("ISO-8859-1"));
 
   net::URLRequestContextBuilder::HttpCacheParams cache_params;
   cache_params.type = net::URLRequestContextBuilder::HttpCacheParams::DISK;
@@ -94,15 +101,6 @@ void AwURLRequestContextGetter::Init() {
 
   url_request_context_.reset(builder.Build());
 
-  url_request_context_->set_accept_language(
-      net::HttpUtil::GenerateAcceptLanguageHeader(
-          content::GetContentClient()->browser()->GetAcceptLangs(
-              browser_context_)));
-
-  // TODO(boliu): Values from chrome/app/resources/locale_settings_en-GB.xtb
-  url_request_context_->set_accept_charset(
-      net::HttpUtil::GenerateAcceptCharsetHeader("ISO-8859-1"));
-
   job_factory_.reset(new AwURLRequestJobFactory);
   bool set_protocol = job_factory_->SetProtocolHandler(
       chrome::kFileScheme, new net::FileProtocolHandler());
diff --git a/chrome/browser/automation/url_request_automation_job.cc b/chrome/browser/automation/url_request_automation_job.cc
index a5c790d..44b7b51 100644
--- a/chrome/browser/automation/url_request_automation_job.cc
+++ b/chrome/browser/automation/url_request_automation_job.cc
@@ -20,6 +20,7 @@
 #include "net/http/http_request_headers.h"
 #include "net/http/http_response_headers.h"
 #include "net/http/http_util.h"
+#include "net/url_request/http_user_agent_settings.h"
 #include "net/url_request/url_request.h"
 #include "net/url_request/url_request_context.h"
 
@@ -53,11 +54,13 @@ net::URLRequest::ProtocolFactory* URLRequestAutomationJob::old_https_factory_
 URLRequestAutomationJob::URLRequestAutomationJob(
     net::URLRequest* request,
     net::NetworkDelegate* network_delegate,
+    const net::HttpUserAgentSettings* http_user_agent_settings,
     int tab,
     int request_id,
     AutomationResourceMessageFilter* filter,
     bool is_pending)
     : net::URLRequestJob(request, network_delegate),
+      http_user_agent_settings_(http_user_agent_settings),
       id_(0),
       tab_(tab),
       message_filter_(filter),
@@ -113,6 +116,7 @@ net::URLRequestJob* URLRequestAutomationJob::Factory(
               child_id, route_id, &details)) {
         URLRequestAutomationJob* job = new URLRequestAutomationJob(
             request, network_delegate,
+            request->context()->http_user_agent_settings(),
             details.tab_handle, info->GetRequestID(), details.filter,
             details.is_pending_render_view);
         return job;
@@ -423,15 +427,22 @@ void URLRequestAutomationJob::StartAsync() {
   // didn't have them specified.
   if (!new_request_headers.HasHeader(
       net::HttpRequestHeaders::kAcceptLanguage) &&
-      !request_->context()->accept_language().empty()) {
-    new_request_headers.SetHeader(net::HttpRequestHeaders::kAcceptLanguage,
-                                  request_->context()->accept_language());
+      http_user_agent_settings_) {
+    std::string accept_language =
+        http_user_agent_settings_->GetAcceptLanguage();
+    if (!accept_language.empty()) {
+      new_request_headers.SetHeader(net::HttpRequestHeaders::kAcceptLanguage,
+                                    accept_language);
+    }
   }
   if (!new_request_headers.HasHeader(
       net::HttpRequestHeaders::kAcceptCharset) &&
-      !request_->context()->accept_charset().empty()) {
-    new_request_headers.SetHeader(net::HttpRequestHeaders::kAcceptCharset,
-                                  request_->context()->accept_charset());
+      http_user_agent_settings_) {
+    std::string accept_charset = http_user_agent_settings_->GetAcceptCharset();
+    if (!accept_charset.empty()) {
+      new_request_headers.SetHeader(net::HttpRequestHeaders::kAcceptCharset,
+                                    accept_charset);
+    }
   }
 
   // Ensure that we do not send username and password fields in the referrer.
diff --git a/chrome/browser/automation/url_request_automation_job.h b/chrome/browser/automation/url_request_automation_job.h
index 9c12f59..ee806b0 100644
--- a/chrome/browser/automation/url_request_automation_job.h
+++ b/chrome/browser/automation/url_request_automation_job.h
@@ -17,6 +17,7 @@ struct AutomationURLResponse;
 namespace net {
 class HttpResponseHeaders;
 class HttpResponseInfo;
+class HttpUserAgentSettings;
 class HostPortPair;
 }
 
@@ -28,12 +29,14 @@ class Message;
 // automation.
 class URLRequestAutomationJob : public net::URLRequestJob {
  public:
-  URLRequestAutomationJob(net::URLRequest* request,
-                          net::NetworkDelegate* network_delegate,
-                          int tab,
-                          int request_id,
-                          AutomationResourceMessageFilter* filter,
-                          bool is_pending);
+  URLRequestAutomationJob(
+      net::URLRequest* request,
+      net::NetworkDelegate* network_delegate,
+      const net::HttpUserAgentSettings* http_user_agent_settings,
+      int tab,
+      int request_id,
+      AutomationResourceMessageFilter* filter,
+      bool is_pending);
 
   // Register our factory for HTTP/HTTPs requests.
   static void EnsureProtocolFactoryRegistered();
@@ -97,6 +100,7 @@ class URLRequestAutomationJob : public net::URLRequestJob {
   // function, which completes the job.
   void NotifyJobCompletionTask();
 
+  const net::HttpUserAgentSettings* http_user_agent_settings_;
   int id_;
   int tab_;
   scoped_refptr<AutomationResourceMessageFilter> message_filter_;
diff --git a/chrome/browser/io_thread.cc b/chrome/browser/io_thread.cc
index 2a774fc..df0d73e 100644
--- a/chrome/browser/io_thread.cc
+++ b/chrome/browser/io_thread.cc
@@ -22,6 +22,7 @@
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/extensions/event_router_forwarder.h"
 #include "chrome/browser/net/async_dns_field_trial.h"
+#include "chrome/browser/net/basic_http_user_agent_settings.h"
 #include "chrome/browser/net/chrome_net_log.h"
 #include "chrome/browser/net/chrome_network_delegate.h"
 #include "chrome/browser/net/chrome_url_request_context.h"
@@ -36,7 +37,6 @@
 #include "chrome/common/chrome_switches.h"
 #include "chrome/common/pref_names.h"
 #include "content/public/browser/browser_thread.h"
-#include "content/public/common/content_client.h"
 #include "net/base/cert_verifier.h"
 #include "net/base/default_server_bound_cert_store.h"
 #include "net/base/host_cache.h"
@@ -83,24 +83,8 @@ void ObserveKeychainEvents() {
 }
 #endif
 
-// Custom URLRequestContext used by requests which aren't associated with a
-// particular profile. We need to use a subclass of URLRequestContext in order
-// to provide the correct User-Agent.
-class URLRequestContextWithUserAgent : public net::URLRequestContext {
- public:
-  virtual const std::string& GetUserAgent(
-      const GURL& url) const OVERRIDE {
-    return content::GetUserAgent(url);
-  }
-
- protected:
-  virtual ~URLRequestContextWithUserAgent() {}
-};
-
-// Used for the "system" URLRequestContext. If this grows more complicated, then
-// consider inheriting directly from URLRequestContext rather than using
-// implementation inheritance.
-class SystemURLRequestContext : public URLRequestContextWithUserAgent {
+// Used for the "system" URLRequestContext.
+class SystemURLRequestContext : public net::URLRequestContext {
  public:
   SystemURLRequestContext() {
 #if defined(USE_NSS)
@@ -194,7 +178,7 @@ scoped_ptr<net::HostResolver> CreateGlobalHostResolver(net::NetLog* net_log) {
 net::URLRequestContext*
 ConstructProxyScriptFetcherContext(IOThread::Globals* globals,
                                    net::NetLog* net_log) {
-  net::URLRequestContext* context = new URLRequestContextWithUserAgent;
+  net::URLRequestContext* context = new net::URLRequestContext;
   context->set_net_log(net_log);
   context->set_host_resolver(globals->host_resolver.get());
   context->set_cert_verifier(globals->cert_verifier.get());
@@ -211,6 +195,8 @@ ConstructProxyScriptFetcherContext(IOThread::Globals* globals,
   context->set_server_bound_cert_service(
       globals->system_server_bound_cert_service.get());
   context->set_network_delegate(globals->system_network_delegate.get());
+  context->set_http_user_agent_settings(
+      globals->http_user_agent_settings.get());
   // TODO(rtenneti): We should probably use HttpServerPropertiesManager for the
   // system URLRequestContext too. There's no reason this should be tied to a
   // profile.
@@ -238,6 +224,8 @@ ConstructSystemRequestContext(IOThread::Globals* globals,
       globals->system_server_bound_cert_service.get());
   context->set_throttler_manager(globals->throttler_manager.get());
   context->set_network_delegate(globals->system_network_delegate.get());
+  context->set_http_user_agent_settings(
+      globals->http_user_agent_settings.get());
   return context;
 }
 
@@ -476,6 +464,8 @@ void IOThread::Init() {
           base::WorkerPool::GetTaskRunner(true)));
   globals_->load_time_stats.reset(new chrome_browser_net::LoadTimeStats());
   globals_->host_mapping_rules.reset(new net::HostMappingRules());
+  globals_->http_user_agent_settings.reset(
+      new BasicHttpUserAgentSettings(EmptyString(), EmptyString()));
   if (command_line.HasSwitch(switches::kHostRules)) {
     globals_->host_mapping_rules->SetRulesFromString(
         command_line.GetSwitchValueASCII(switches::kHostRules));
diff --git a/chrome/browser/io_thread.h b/chrome/browser/io_thread.h
index 6e0699c..ae1af7d 100644
--- a/chrome/browser/io_thread.h
+++ b/chrome/browser/io_thread.h
@@ -41,6 +41,7 @@ class HostResolver;
 class HttpAuthHandlerFactory;
 class HttpServerProperties;
 class HttpTransactionFactory;
+class HttpUserAgentSettings;
 class NetworkDelegate;
 class ServerBoundCertService;
 class ProxyConfigService;
@@ -115,6 +116,7 @@ class IOThread : public content::BrowserThreadDelegate {
         http_pipelining_compatibility_client;
     scoped_ptr<chrome_browser_net::LoadTimeStats> load_time_stats;
     scoped_ptr<net::HostMappingRules> host_mapping_rules;
+    scoped_ptr<net::HttpUserAgentSettings> http_user_agent_settings;
     bool ignore_certificate_errors;
     bool http_pipelining_enabled;
     uint16 testing_fixed_http_port;
diff --git a/chrome/browser/net/basic_http_user_agent_settings.cc b/chrome/browser/net/basic_http_user_agent_settings.cc
new file mode 100644
index 0000000..093ee58
--- /dev/null
+++ b/chrome/browser/net/basic_http_user_agent_settings.cc
@@ -0,0 +1,29 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "chrome/browser/net/basic_http_user_agent_settings.h"
+
+#include "content/public/common/content_client.h"
+
+BasicHttpUserAgentSettings::BasicHttpUserAgentSettings(
+    const std::string& accept_language, const std::string& accept_charset)
+    : accept_language_(accept_language),
+      accept_charset_(accept_charset) {
+}
+
+BasicHttpUserAgentSettings::~BasicHttpUserAgentSettings() {
+}
+
+std::string BasicHttpUserAgentSettings::GetAcceptLanguage() const {
+  return accept_language_;
+}
+
+std::string BasicHttpUserAgentSettings::GetAcceptCharset() const {
+  return accept_charset_;
+}
+
+std::string BasicHttpUserAgentSettings::GetUserAgent(const GURL& url) const {
+  return content::GetUserAgent(url);
+}
+
diff --git a/chrome/browser/net/basic_http_user_agent_settings.h b/chrome/browser/net/basic_http_user_agent_settings.h
new file mode 100644
index 0000000..c7a6d59
--- /dev/null
+++ b/chrome/browser/net/basic_http_user_agent_settings.h
@@ -0,0 +1,36 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CHROME_BROWSER_NET_BASIC_HTTP_USER_AGENT_SETTINGS_H_
+#define CHROME_BROWSER_NET_BASIC_HTTP_USER_AGENT_SETTINGS_H_
+
+#include <string>
+
+#include "base/basictypes.h"
+#include "base/compiler_specific.h"
+#include "net/url_request/http_user_agent_settings.h"
+
+// An implementation of |HttpUserAgentSettings| that provides fixed values for
+// the HTTP headers Accept-Language and Accept-Charset and uses
+// |content::GetUserAgent| to provide the HTTP User-Agent header value.
+class BasicHttpUserAgentSettings : public net::HttpUserAgentSettings {
+ public:
+  BasicHttpUserAgentSettings(const std::string& accept_language,
+                             const std::string& accept_charset);
+  virtual ~BasicHttpUserAgentSettings();
+
+  // HttpUserAgentSettings implementation
+  virtual std::string GetAcceptLanguage() const OVERRIDE;
+  virtual std::string GetAcceptCharset() const OVERRIDE;
+  virtual std::string GetUserAgent(const GURL& url) const OVERRIDE;
+
+ private:
+  const std::string accept_language_;
+  const std::string accept_charset_;
+
+  DISALLOW_COPY_AND_ASSIGN(BasicHttpUserAgentSettings);
+};
+
+#endif  // CHROME_BROWSER_NET_BASIC_HTTP_USER_AGENT_SETTINGS_H_
+
diff --git a/chrome/browser/net/chrome_http_user_agent_settings.cc b/chrome/browser/net/chrome_http_user_agent_settings.cc
new file mode 100644
index 0000000..5141cb04c
--- /dev/null
+++ b/chrome/browser/net/chrome_http_user_agent_settings.cc
@@ -0,0 +1,67 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "chrome/browser/net/chrome_http_user_agent_settings.h"
+
+#include "chrome/browser/prefs/pref_service.h"
+#include "chrome/common/pref_names.h"
+#include "content/public/browser/browser_thread.h"
+#include "content/public/common/content_client.h"
+#include "net/http/http_util.h"
+
+ChromeHttpUserAgentSettings::ChromeHttpUserAgentSettings(PrefService* prefs) {
+  DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
+  pref_accept_language_.Init(prefs::kAcceptLanguages, prefs, NULL);
+  pref_accept_charset_.Init(prefs::kDefaultCharset, prefs, NULL);
+  last_pref_accept_language_ = *pref_accept_language_;
+  last_http_accept_language_ =
+      net::HttpUtil::GenerateAcceptLanguageHeader(last_pref_accept_language_);
+  last_pref_accept_charset_ = *pref_accept_charset_;
+  last_http_accept_charset_ =
+      net::HttpUtil::GenerateAcceptCharsetHeader(last_pref_accept_charset_);
+  pref_accept_language_.MoveToThread(
+      content::BrowserThread::GetMessageLoopProxyForThread(
+          content::BrowserThread::IO));
+  pref_accept_charset_.MoveToThread(
+      content::BrowserThread::GetMessageLoopProxyForThread(
+          content::BrowserThread::IO));
+}
+
+ChromeHttpUserAgentSettings::~ChromeHttpUserAgentSettings() {
+  DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::IO));
+}
+
+void ChromeHttpUserAgentSettings::CleanupOnUIThread() {
+  DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
+  pref_accept_language_.Destroy();
+  pref_accept_charset_.Destroy();
+}
+
+std::string ChromeHttpUserAgentSettings::GetAcceptLanguage() const {
+  DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::IO));
+  std::string new_pref_accept_language = *pref_accept_language_;
+  if (new_pref_accept_language != last_pref_accept_language_) {
+    last_http_accept_language_ =
+        net::HttpUtil::GenerateAcceptLanguageHeader(new_pref_accept_language);
+    last_pref_accept_language_ = new_pref_accept_language;
+  }
+  return last_http_accept_language_;
+}
+
+std::string ChromeHttpUserAgentSettings::GetAcceptCharset() const {
+  DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::IO));
+  std::string new_pref_accept_charset = *pref_accept_charset_;
+  if (new_pref_accept_charset != last_pref_accept_charset_) {
+    last_http_accept_charset_ =
+        net::HttpUtil::GenerateAcceptCharsetHeader(new_pref_accept_charset);
+    last_pref_accept_charset_ = new_pref_accept_charset;
+  }
+  return last_http_accept_charset_;
+}
+
+std::string ChromeHttpUserAgentSettings::GetUserAgent(const GURL& url) const {
+  DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::IO));
+  return content::GetUserAgent(url);
+}
+
diff --git a/chrome/browser/net/chrome_http_user_agent_settings.h b/chrome/browser/net/chrome_http_user_agent_settings.h
new file mode 100644
index 0000000..a7d390f
--- /dev/null
+++ b/chrome/browser/net/chrome_http_user_agent_settings.h
@@ -0,0 +1,49 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CHROME_BROWSER_NET_CHROME_HTTP_USER_AGENT_SETTINGS_H_
+#define CHROME_BROWSER_NET_CHROME_HTTP_USER_AGENT_SETTINGS_H_
+
+#include <string>
+
+#include "base/basictypes.h"
+#include "base/compiler_specific.h"
+#include "chrome/browser/api/prefs/pref_member.h"
+#include "net/url_request/http_user_agent_settings.h"
+
+class PrefService;
+
+// An implementation of |HttpUserAgentSettings| that provides HTTP headers
+// Accept-Language and Accept-Charset values that track Pref settings and uses
+// |content::GetUserAgent| to provide the HTTP User-Agent header value.
+class ChromeHttpUserAgentSettings : public net::HttpUserAgentSettings {
+ public:
+  // Must be called on the UI thread.
+  explicit ChromeHttpUserAgentSettings(PrefService* prefs);
+  // Must be called on the IO thread.
+  virtual ~ChromeHttpUserAgentSettings();
+
+  void CleanupOnUIThread();
+
+  // net::HttpUserAgentSettings implementation
+  virtual std::string GetAcceptLanguage() const OVERRIDE;
+  virtual std::string GetAcceptCharset() const OVERRIDE;
+  virtual std::string GetUserAgent(const GURL& url) const OVERRIDE;
+
+ private:
+  StringPrefMember pref_accept_language_;
+  StringPrefMember pref_accept_charset_;
+
+  // Avoid re-processing by caching the last value from the preferences and the
+  // last result of processing via net::HttpUtil::GenerateAccept*Header().
+  mutable std::string last_pref_accept_language_;
+  mutable std::string last_http_accept_language_;
+  mutable std::string last_pref_accept_charset_;
+  mutable std::string last_http_accept_charset_;
+
+  DISALLOW_COPY_AND_ASSIGN(ChromeHttpUserAgentSettings);
+};
+
+#endif  // CHROME_BROWSER_NET_CHROME_HTTP_USER_AGENT_SETTINGS_H_
+
diff --git a/chrome/browser/net/chrome_url_request_context.cc b/chrome/browser/net/chrome_url_request_context.cc
index 3130ed2..677ed0a 100644
--- a/chrome/browser/net/chrome_url_request_context.cc
+++ b/chrome/browser/net/chrome_url_request_context.cc
@@ -11,18 +11,11 @@
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/io_thread.h"
 #include "chrome/browser/net/load_time_stats.h"
-#include "chrome/browser/prefs/pref_service.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/profiles/profile_io_data.h"
 #include "chrome/browser/profiles/storage_partition_descriptor.h"
-#include "chrome/common/chrome_notification_types.h"
-#include "chrome/common/pref_names.h"
 #include "content/public/browser/browser_thread.h"
-#include "content/public/browser/notification_details.h"
-#include "content/public/browser/notification_source.h"
-#include "content/public/common/content_client.h"
 #include "net/cookies/cookie_store.h"
-#include "net/http/http_util.h"
 
 using content::BrowserThread;
 
@@ -156,19 +149,12 @@ class FactoryForMedia : public ChromeURLRequestContextFactory {
 // ----------------------------------------------------------------------------
 
 ChromeURLRequestContextGetter::ChromeURLRequestContextGetter(
-    Profile* profile,
     ChromeURLRequestContextFactory* factory)
     : factory_(factory) {
   DCHECK(factory);
-  DCHECK(profile);
-  RegisterPrefsObserver(profile);
 }
 
-ChromeURLRequestContextGetter::~ChromeURLRequestContextGetter() {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
-
-  DCHECK(registrar_.IsEmpty()) << "Probably didn't call CleanupOnUIThread";
-}
+ChromeURLRequestContextGetter::~ChromeURLRequestContextGetter() {}
 
 // Lazily create a ChromeURLRequestContext using our factory.
 net::URLRequestContext* ChromeURLRequestContextGetter::GetURLRequestContext() {
@@ -198,7 +184,6 @@ ChromeURLRequestContextGetter* ChromeURLRequestContextGetter::CreateOriginal(
     const ProfileIOData* profile_io_data) {
   DCHECK(!profile->IsOffTheRecord());
   return new ChromeURLRequestContextGetter(
-      profile,
       new FactoryForMain(profile_io_data));
 }
 
@@ -208,7 +193,6 @@ ChromeURLRequestContextGetter::CreateOriginalForMedia(
     Profile* profile, const ProfileIOData* profile_io_data) {
   DCHECK(!profile->IsOffTheRecord());
   return new ChromeURLRequestContextGetter(
-      profile,
       new FactoryForMedia(profile_io_data));
 }
 
@@ -218,7 +202,6 @@ ChromeURLRequestContextGetter::CreateOriginalForExtensions(
     Profile* profile, const ProfileIOData* profile_io_data) {
   DCHECK(!profile->IsOffTheRecord());
   return new ChromeURLRequestContextGetter(
-      profile,
       new FactoryForExtensions(profile_io_data));
 }
 
@@ -234,7 +217,6 @@ ChromeURLRequestContextGetter::CreateOriginalForIsolatedApp(
   ChromeURLRequestContextGetter* main_context =
       static_cast<ChromeURLRequestContextGetter*>(profile->GetRequestContext());
   return new ChromeURLRequestContextGetter(
-      profile,
       new FactoryForIsolatedApp(profile_io_data, partition_descriptor,
            main_context, protocol_handler_interceptor.Pass()));
 }
@@ -248,7 +230,6 @@ ChromeURLRequestContextGetter::CreateOriginalForIsolatedMedia(
     const StoragePartitionDescriptor& partition_descriptor) {
   DCHECK(!profile->IsOffTheRecord());
   return new ChromeURLRequestContextGetter(
-      profile,
       new FactoryForIsolatedMedia(
           profile_io_data, partition_descriptor, app_context));
 }
@@ -259,7 +240,7 @@ ChromeURLRequestContextGetter::CreateOffTheRecord(
     Profile* profile, const ProfileIOData* profile_io_data) {
   DCHECK(profile->IsOffTheRecord());
   return new ChromeURLRequestContextGetter(
-      profile, new FactoryForMain(profile_io_data));
+      new FactoryForMain(profile_io_data));
 }
 
 // static
@@ -268,7 +249,7 @@ ChromeURLRequestContextGetter::CreateOffTheRecordForExtensions(
     Profile* profile, const ProfileIOData* profile_io_data) {
   DCHECK(profile->IsOffTheRecord());
   return new ChromeURLRequestContextGetter(
-      profile, new FactoryForExtensions(profile_io_data));
+      new FactoryForExtensions(profile_io_data));
 }
 
 // static
@@ -283,62 +264,10 @@ ChromeURLRequestContextGetter::CreateOffTheRecordForIsolatedApp(
   ChromeURLRequestContextGetter* main_context =
       static_cast<ChromeURLRequestContextGetter*>(profile->GetRequestContext());
   return new ChromeURLRequestContextGetter(
-      profile,
       new FactoryForIsolatedApp(profile_io_data, partition_descriptor,
           main_context, protocol_handler_interceptor.Pass()));
 }
 
-void ChromeURLRequestContextGetter::CleanupOnUIThread() {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
-  // Unregister for pref notifications.
-  DCHECK(!registrar_.IsEmpty()) << "Called more than once!";
-  registrar_.RemoveAll();
-}
-
-void ChromeURLRequestContextGetter::OnPreferenceChanged(
-    PrefServiceBase* prefs,
-    const std::string& pref_name_in) {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
-
-  DCHECK(prefs);
-  if (pref_name_in == prefs::kAcceptLanguages) {
-    std::string accept_language =
-        prefs->GetString(prefs::kAcceptLanguages);
-    BrowserThread::PostTask(
-        BrowserThread::IO, FROM_HERE,
-        base::Bind(
-            &ChromeURLRequestContextGetter::OnAcceptLanguageChange,
-            this,
-            accept_language));
-  } else if (pref_name_in == prefs::kDefaultCharset) {
-    std::string default_charset = prefs->GetString(prefs::kDefaultCharset);
-    BrowserThread::PostTask(
-        BrowserThread::IO, FROM_HERE,
-        base::Bind(
-            &ChromeURLRequestContextGetter::OnDefaultCharsetChange,
-            this,
-            default_charset));
-  }
-}
-
-void ChromeURLRequestContextGetter::RegisterPrefsObserver(Profile* profile) {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
-
-  registrar_.Init(profile->GetPrefs());
-  registrar_.Add(prefs::kAcceptLanguages, this);
-  registrar_.Add(prefs::kDefaultCharset, this);
-}
-
-void ChromeURLRequestContextGetter::OnAcceptLanguageChange(
-    const std::string& accept_language) {
-  GetIOContext()->OnAcceptLanguageChange(accept_language);
-}
-
-void ChromeURLRequestContextGetter::OnDefaultCharsetChange(
-    const std::string& default_charset) {
-  GetIOContext()->OnDefaultCharsetChange(default_charset);
-}
-
 // ----------------------------------------------------------------------------
 // ChromeURLRequestContext
 // ----------------------------------------------------------------------------
@@ -379,22 +308,3 @@ void ChromeURLRequestContext::set_chrome_url_data_manager_backend(
   DCHECK(backend);
   chrome_url_data_manager_backend_ = backend;
 }
-
-const std::string& ChromeURLRequestContext::GetUserAgent(
-    const GURL& url) const {
-  return content::GetUserAgent(url);
-}
-
-void ChromeURLRequestContext::OnAcceptLanguageChange(
-    const std::string& accept_language) {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
-  set_accept_language(
-      net::HttpUtil::GenerateAcceptLanguageHeader(accept_language));
-}
-
-void ChromeURLRequestContext::OnDefaultCharsetChange(
-    const std::string& default_charset) {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
-  set_accept_charset(
-      net::HttpUtil::GenerateAcceptCharsetHeader(default_charset));
-}
diff --git a/chrome/browser/net/chrome_url_request_context.h b/chrome/browser/net/chrome_url_request_context.h
index 90ee941..93ce806 100644
--- a/chrome/browser/net/chrome_url_request_context.h
+++ b/chrome/browser/net/chrome_url_request_context.h
@@ -8,8 +8,6 @@
 #include <string>
 
 #include "base/memory/scoped_ptr.h"
-#include "base/prefs/public/pref_change_registrar.h"
-#include "base/prefs/public/pref_observer.h"
 #include "net/url_request/url_request_context.h"
 #include "net/url_request/url_request_context_getter.h"
 #include "net/url_request/url_request_job_factory.h"
@@ -53,8 +51,6 @@ class ChromeURLRequestContext : public net::URLRequestContext {
     return is_incognito_;
   }
 
-  virtual const std::string& GetUserAgent(const GURL& url) const OVERRIDE;
-
   // TODO(willchan): Get rid of the need for this accessor. Really, this should
   // move completely to ProfileIOData.
   ChromeURLDataManagerBackend* chrome_url_data_manager_backend() const;
@@ -66,12 +62,6 @@ class ChromeURLRequestContext : public net::URLRequestContext {
   void set_chrome_url_data_manager_backend(
       ChromeURLDataManagerBackend* backend);
 
-  // Callback for when the accept language changes.
-  void OnAcceptLanguageChange(const std::string& accept_language);
-
-  // Callback for when the default charset changes.
-  void OnDefaultCharsetChange(const std::string& default_charset);
-
  private:
   base::WeakPtrFactory<ChromeURLRequestContext> weak_factory_;
 
@@ -98,16 +88,12 @@ class ChromeURLRequestContext : public net::URLRequestContext {
 //
 // Most methods are expected to be called on the UI thread, except for
 // the destructor and GetURLRequestContext().
-class ChromeURLRequestContextGetter : public net::URLRequestContextGetter,
-                                      public PrefObserver {
+class ChromeURLRequestContextGetter : public net::URLRequestContextGetter {
  public:
   // Constructs a ChromeURLRequestContextGetter that will use |factory| to
-  // create the ChromeURLRequestContext. If |profile| is non-NULL, then the
-  // ChromeURLRequestContextGetter will additionally watch the preferences for
-  // changes to charset/language and CleanupOnUIThread() will need to be
-  // called to unregister.
-  ChromeURLRequestContextGetter(Profile* profile,
-                                ChromeURLRequestContextFactory* factory);
+  // create the ChromeURLRequestContext.
+  explicit ChromeURLRequestContextGetter(
+      ChromeURLRequestContextFactory* factory);
 
   // Note that GetURLRequestContext() can only be called from the IO
   // thread (it will assert otherwise).
@@ -176,29 +162,9 @@ class ChromeURLRequestContextGetter : public net::URLRequestContextGetter,
       scoped_ptr<net::URLRequestJobFactory::Interceptor>
           protocol_handler_interceptor);
 
-  // Clean up UI thread resources. This is expected to get called on the UI
-  // thread before the instance is deleted on the IO thread.
-  void CleanupOnUIThread();
-
-  // PrefObserver implementation.
-  virtual void OnPreferenceChanged(PrefServiceBase* service,
-                                   const std::string& pref_name) OVERRIDE;
-
  private:
-  // Must be called on the IO thread.
   virtual ~ChromeURLRequestContextGetter();
 
-  // Registers an observer on |profile|'s preferences which will be used
-  // to update the context when the default language and charset change.
-  void RegisterPrefsObserver(Profile* profile);
-
-  // These methods simply forward to the corresponding method on
-  // ChromeURLRequestContext.
-  void OnAcceptLanguageChange(const std::string& accept_language);
-  void OnDefaultCharsetChange(const std::string& default_charset);
-
-  PrefChangeRegistrar registrar_;
-
   // Deferred logic for creating a ChromeURLRequestContext.
   // Access only from the IO thread.
   scoped_ptr<ChromeURLRequestContextFactory> factory_;
diff --git a/chrome/browser/policy/device_management_service.cc b/chrome/browser/policy/device_management_service.cc
index bbc7a07..18245b3 100644
--- a/chrome/browser/policy/device_management_service.cc
+++ b/chrome/browser/policy/device_management_service.cc
@@ -13,6 +13,7 @@
 #include "base/stringprintf.h"
 #include "base/sys_info.h"
 #include "chrome/browser/browser_process.h"
+#include "chrome/browser/net/basic_http_user_agent_settings.h"
 #include "chrome/browser/net/chrome_net_log.h"
 #include "chrome/common/chrome_version_info.h"
 #include "content/public/browser/browser_thread.h"
@@ -185,12 +186,13 @@ class DeviceManagementRequestContext : public net::URLRequestContext {
   virtual ~DeviceManagementRequestContext();
 
  private:
-  // Overridden from net::URLRequestContext:
-  virtual const std::string& GetUserAgent(const GURL& url) const OVERRIDE;
+  BasicHttpUserAgentSettings basic_http_user_agent_settings_;
 };
 
 DeviceManagementRequestContext::DeviceManagementRequestContext(
-    net::URLRequestContext* base_context) {
+    net::URLRequestContext* base_context)
+    // Use sane Accept-Language and Accept-Charset values for our purposes.
+    : basic_http_user_agent_settings_("*", "*") {
   // Share resolver, proxy service and ssl bits with the baseline context. This
   // is important so we don't make redundant requests (e.g. when resolving proxy
   // auto configuration).
@@ -207,20 +209,13 @@ DeviceManagementRequestContext::DeviceManagementRequestContext(
   // No cookies, please.
   set_cookie_store(new net::CookieMonster(NULL, NULL));
 
-  // Initialize these to sane values for our purposes.
-  set_accept_language("*");
-  set_accept_charset("*");
+  set_http_user_agent_settings(&basic_http_user_agent_settings_);
 }
 
 DeviceManagementRequestContext::~DeviceManagementRequestContext() {
   delete http_transaction_factory();
 }
 
-const std::string& DeviceManagementRequestContext::GetUserAgent(
-    const GURL& url) const {
-  return content::GetUserAgent(url);
-}
-
 // Request context holder.
 class DeviceManagementRequestContextGetter
     : public net::URLRequestContextGetter {
diff --git a/chrome/browser/profiles/off_the_record_profile_io_data.cc b/chrome/browser/profiles/off_the_record_profile_io_data.cc
index 88dcf1f..3be7f61 100644
--- a/chrome/browser/profiles/off_the_record_profile_io_data.cc
+++ b/chrome/browser/profiles/off_the_record_profile_io_data.cc
@@ -47,19 +47,6 @@ OffTheRecordProfileIOData::Handle::Handle(Profile* profile)
 
 OffTheRecordProfileIOData::Handle::~Handle() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
-  if (main_request_context_getter_)
-    main_request_context_getter_->CleanupOnUIThread();
-  if (extensions_request_context_getter_)
-    extensions_request_context_getter_->CleanupOnUIThread();
-
-  // Clean up all isolated app request contexts.
-  for (ChromeURLRequestContextGetterMap::iterator iter =
-           app_request_context_getter_map_.begin();
-       iter != app_request_context_getter_map_.end();
-       ++iter) {
-    iter->second->CleanupOnUIThread();
-  }
-
   io_data_->ShutdownOnUIThread();
 }
 
diff --git a/chrome/browser/profiles/profile_impl_io_data.cc b/chrome/browser/profiles/profile_impl_io_data.cc
index 2a53927..65e8822 100644
--- a/chrome/browser/profiles/profile_impl_io_data.cc
+++ b/chrome/browser/profiles/profile_impl_io_data.cc
@@ -51,13 +51,6 @@ ProfileImplIOData::Handle::Handle(Profile* profile)
 
 ProfileImplIOData::Handle::~Handle() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
-  if (main_request_context_getter_)
-    main_request_context_getter_->CleanupOnUIThread();
-  if (media_request_context_getter_)
-    media_request_context_getter_->CleanupOnUIThread();
-  if (extensions_request_context_getter_)
-    extensions_request_context_getter_->CleanupOnUIThread();
-
   if (io_data_->predictor_.get() != NULL) {
     // io_data_->predictor_ might be NULL if Init() was never called
     // (i.e. we shut down before ProfileImpl::DoFinalInit() got called).
@@ -65,22 +58,6 @@ ProfileImplIOData::Handle::~Handle() {
     io_data_->predictor_->ShutdownOnUIThread(user_prefs);
   }
 
-  // Clean up all isolated app request contexts.
-  for (ChromeURLRequestContextGetterMap::iterator iter =
-           app_request_context_getter_map_.begin();
-       iter != app_request_context_getter_map_.end();
-       ++iter) {
-    iter->second->CleanupOnUIThread();
-  }
-
-  // Clean up all isolated media request contexts.
-  for (ChromeURLRequestContextGetterMap::iterator iter =
-           isolated_media_request_context_getter_map_.begin();
-       iter != isolated_media_request_context_getter_map_.end();
-       ++iter) {
-    iter->second->CleanupOnUIThread();
-  }
-
   if (io_data_->http_server_properties_manager())
     io_data_->http_server_properties_manager()->ShutdownOnUIThread();
   io_data_->ShutdownOnUIThread();
diff --git a/chrome/browser/profiles/profile_io_data.cc b/chrome/browser/profiles/profile_io_data.cc
index a03ed92..dab854fb 100644
--- a/chrome/browser/profiles/profile_io_data.cc
+++ b/chrome/browser/profiles/profile_io_data.cc
@@ -31,6 +31,7 @@
 #include "chrome/browser/io_thread.h"
 #include "chrome/browser/net/chrome_cookie_notification_details.h"
 #include "chrome/browser/net/chrome_fraudulent_certificate_reporter.h"
+#include "chrome/browser/net/chrome_http_user_agent_settings.h"
 #include "chrome/browser/net/chrome_net_log.h"
 #include "chrome/browser/net/chrome_network_delegate.h"
 #include "chrome/browser/net/http_server_properties_manager.h"
@@ -145,13 +146,6 @@ void ProfileIOData::InitializeOnUIThread(Profile* profile) {
   scoped_ptr<ProfileParams> params(new ProfileParams);
   params->path = profile->GetPath();
 
-  // Set up Accept-Language and Accept-Charset header values
-  params->accept_language = net::HttpUtil::GenerateAcceptLanguageHeader(
-      pref_service->GetString(prefs::kAcceptLanguages));
-  std::string default_charset = pref_service->GetString(prefs::kDefaultCharset);
-  params->accept_charset =
-      net::HttpUtil::GenerateAcceptCharsetHeader(default_charset);
-
   params->io_thread = g_browser_process->io_thread();
 
   params->cookie_settings = CookieSettings::Factory::GetForProfile(profile);
@@ -204,6 +198,8 @@ void ProfileIOData::InitializeOnUIThread(Profile* profile) {
   printing_enabled_.MoveToThread(
       BrowserThread::GetMessageLoopProxyForThread(BrowserThread::IO));
 #endif
+  chrome_http_user_agent_settings_.reset(
+      new ChromeHttpUserAgentSettings(pref_service));
 
   // The URLBlacklistManager has to be created on the UI thread to register
   // observers of |pref_service|, and it also has to clean up on
@@ -583,8 +579,8 @@ void ProfileIOData::LazyInitialize() const {
 void ProfileIOData::ApplyProfileParamsToContext(
     ChromeURLRequestContext* context) const {
   context->set_is_incognito(is_incognito());
-  context->set_accept_language(profile_params_->accept_language);
-  context->set_accept_charset(profile_params_->accept_charset);
+  context->set_http_user_agent_settings(
+      chrome_http_user_agent_settings_.get());
   context->set_ssl_config_service(profile_params_->ssl_config_service);
 }
 
@@ -668,6 +664,8 @@ void ProfileIOData::ShutdownOnUIThread() {
   if (url_blacklist_manager_.get())
     url_blacklist_manager_->ShutdownOnUIThread();
 #endif
+  if (chrome_http_user_agent_settings_.get())
+    chrome_http_user_agent_settings_->CleanupOnUIThread();
   bool posted = BrowserThread::DeleteSoon(BrowserThread::IO, FROM_HERE, this);
   if (!posted)
     delete this;
diff --git a/chrome/browser/profiles/profile_io_data.h b/chrome/browser/profiles/profile_io_data.h
index fbdd845..354c86b 100644
--- a/chrome/browser/profiles/profile_io_data.h
+++ b/chrome/browser/profiles/profile_io_data.h
@@ -23,6 +23,7 @@
 #include "net/http/http_network_session.h"
 #include "net/url_request/url_request_job_factory.h"
 
+class ChromeHttpUserAgentSettings;
 class CookieSettings;
 class DesktopNotificationService;
 class ExtensionInfoMap;
@@ -186,8 +187,6 @@ class ProfileIOData {
     ~ProfileParams();
 
     FilePath path;
-    std::string accept_language;
-    std::string accept_charset;
     IOThread* io_thread;
     scoped_refptr<CookieSettings> cookie_settings;
     scoped_refptr<net::SSLConfigService> ssl_config_service;
@@ -428,6 +427,9 @@ class ProfileIOData {
   mutable scoped_ptr<chrome_browser_net::ResourcePrefetchPredictorObserver>
       resource_prefetch_predictor_observer_;
 
+  mutable scoped_ptr<ChromeHttpUserAgentSettings>
+      chrome_http_user_agent_settings_;
+
   mutable chrome_browser_net::LoadTimeStats* load_time_stats_;
 
   // TODO(jhawkins): Remove once crbug.com/102004 is fixed.
diff --git a/chrome/browser/safe_browsing/safe_browsing_service.cc b/chrome/browser/safe_browsing/safe_browsing_service.cc
index 45a5a86..3b112d2 100644
--- a/chrome/browser/safe_browsing/safe_browsing_service.cc
+++ b/chrome/browser/safe_browsing/safe_browsing_service.cc
@@ -100,22 +100,6 @@ FilePath CookieFilePath() {
 
 }  // namespace
 
-// Custom URLRequestContext used by SafeBrowsing requests, which are not
-// associated with a particular profile. We need to use a subclass of
-// URLRequestContext in order to provide the correct User-Agent.
-class SafeBrowsingURLRequestContext : public net::URLRequestContext {
- public:
-  virtual const std::string& GetUserAgent(
-      const GURL& url) const OVERRIDE {
-    return content::GetUserAgent(url);
-  }
-
- private:
-  virtual ~SafeBrowsingURLRequestContext() {}
-
-  base::debug::LeakTracker<SafeBrowsingURLRequestContext> leak_tracker_;
-};
-
 class SafeBrowsingURLRequestContextGetter
     : public net::URLRequestContextGetter {
  public:
@@ -624,11 +608,12 @@ void SafeBrowsingService::InitURLRequestContextOnIOThread(
       new SQLitePersistentCookieStore(CookieFilePath(), false, NULL),
       NULL);
 
-  url_request_context_.reset(new SafeBrowsingURLRequestContext);
+  url_request_context_.reset(new net::URLRequestContext);
   // |system_url_request_context_getter| may be NULL during tests.
-  if (system_url_request_context_getter)
+  if (system_url_request_context_getter) {
     url_request_context_->CopyFrom(
         system_url_request_context_getter->GetURLRequestContext());
+  }
   url_request_context_->set_cookie_store(cookie_store);
 }
 
diff --git a/chrome/chrome_browser.gypi b/chrome/chrome_browser.gypi
index b3e8ebd..dc6f528 100644
--- a/chrome/chrome_browser.gypi
+++ b/chrome/chrome_browser.gypi
@@ -1038,9 +1038,13 @@
         'browser/net/about_protocol_handler.h',
         'browser/net/async_dns_field_trial.cc',
         'browser/net/async_dns_field_trial.h',
+        'browser/net/basic_http_user_agent_settings.cc',
+        'browser/net/basic_http_user_agent_settings.h',
         'browser/net/chrome_cookie_notification_details.h',
         'browser/net/chrome_fraudulent_certificate_reporter.cc',
         'browser/net/chrome_fraudulent_certificate_reporter.h',
+        'browser/net/chrome_http_user_agent_settings.cc',
+        'browser/net/chrome_http_user_agent_settings.h',
         'browser/net/chrome_net_log.cc',
         'browser/net/chrome_net_log.h',
         'browser/net/chrome_network_delegate.cc',
diff --git a/chrome/service/net/service_url_request_context.cc b/chrome/service/net/service_url_request_context.cc
index e05b7b9..3bb5565 100644
--- a/chrome/service/net/service_url_request_context.cc
+++ b/chrome/service/net/service_url_request_context.cc
@@ -25,6 +25,7 @@
 #include "net/http/http_server_properties_impl.h"
 #include "net/proxy/proxy_config_service.h"
 #include "net/proxy/proxy_service.h"
+#include "net/url_request/static_http_user_agent_settings.h"
 #include "net/url_request/url_request_throttler_manager.h"
 
 namespace {
@@ -108,8 +109,7 @@ std::string MakeUserAgentForServiceProcess() {
 ServiceURLRequestContext::ServiceURLRequestContext(
     const std::string& user_agent,
     net::ProxyConfigService* net_proxy_config_service)
-    : user_agent_(user_agent),
-      ALLOW_THIS_IN_INITIALIZER_LIST(storage_(this)) {
+    : ALLOW_THIS_IN_INITIALIZER_LIST(storage_(this)) {
   storage_.set_host_resolver(net::HostResolver::CreateDefaultResolver(NULL));
   storage_.set_proxy_service(net::ProxyService::CreateUsingSystemProxyResolver(
       net_proxy_config_service, 0u, NULL));
@@ -138,16 +138,8 @@ ServiceURLRequestContext::ServiceURLRequestContext(
           net::HttpCache::DefaultBackend::InMemory(0)));
   // In-memory cookie store.
   storage_.set_cookie_store(new net::CookieMonster(NULL, NULL));
-  set_accept_language("en-us,fr");
-  set_accept_charset("iso-8859-1,*,utf-8");
-}
-
-const std::string& ServiceURLRequestContext::GetUserAgent(
-    const GURL& url) const {
-  // If the user agent is set explicitly return that, otherwise call the
-  // base class method to return default value.
-  return user_agent_.empty() ?
-      net::URLRequestContext::GetUserAgent(url) : user_agent_;
+  storage_.set_http_user_agent_settings(new net::StaticHttpUserAgentSettings(
+      "en-us,fr", "iso-8859-1,*,utf-8", user_agent));
 }
 
 ServiceURLRequestContext::~ServiceURLRequestContext() {
diff --git a/chrome/service/net/service_url_request_context.h b/chrome/service/net/service_url_request_context.h
index 6fa2429..aa06778 100644
--- a/chrome/service/net/service_url_request_context.h
+++ b/chrome/service/net/service_url_request_context.h
@@ -41,11 +41,7 @@ class ServiceURLRequestContext : public net::URLRequestContext {
 
   virtual ~ServiceURLRequestContext();
 
-  // Overridden from net::URLRequestContext:
-  virtual const std::string& GetUserAgent(const GURL& url) const OVERRIDE;
-
  private:
-  std::string user_agent_;
   net::URLRequestContextStorage storage_;
 };
 
diff --git a/chrome_frame/test/net/fake_external_tab.cc b/chrome_frame/test/net/fake_external_tab.cc
index 1f6c808..87f3065 100644
--- a/chrome_frame/test/net/fake_external_tab.cc
+++ b/chrome_frame/test/net/fake_external_tab.cc
@@ -264,9 +264,10 @@ void FilterDisabledTests() {
     "URLRequestTestHTTP.ProxyTunnelRedirectTest",
     "URLRequestTestHTTP.UnexpectedServerAuthTest",
 
-    // This test is disabled as it expects an empty UA to be echoed back from
-    // the server which is not the case in ChromeFrame.
+    // These tests are disabled as they expect an empty UA to be echoed back
+    // from the server which is not the case in ChromeFrame.
     "URLRequestTestHTTP.DefaultUserAgent",
+    "URLRequestTestHTTP.EmptyHttpUserAgentSettings",
     // This test modifies the UploadData object after it has been marshaled to
     // ChromeFrame. We don't support this.
     "URLRequestTestHTTP.TestPostChunkedDataAfterStart",
diff --git a/chrome_frame/test/net/test_automation_provider.cc b/chrome_frame/test/net/test_automation_provider.cc
index 9012a19..7b94536 100644
--- a/chrome_frame/test/net/test_automation_provider.cc
+++ b/chrome_frame/test/net/test_automation_provider.cc
@@ -9,6 +9,7 @@
 #include "base/path_service.h"
 #include "chrome/common/automation_messages.h"
 #include "chrome_frame/test/net/test_automation_resource_message_filter.h"
+#include "net/url_request/url_request_context.h"
 
 namespace {
 
@@ -93,6 +94,7 @@ net::URLRequestJob* TestAutomationProvider::Factory(
       static int new_id = 0x00100000;
       URLRequestAutomationJob* job = new URLRequestAutomationJob(
           request, network_delegate,
+          request->context()->http_user_agent_settings(),
           g_provider_instance_->tab_handle_, new_id++,
           g_provider_instance_->automation_resource_message_filter_, false);
       return job;
diff --git a/content/browser/speech/google_one_shot_remote_engine.cc b/content/browser/speech/google_one_shot_remote_engine.cc
index d713dfd..73e621e 100644
--- a/content/browser/speech/google_one_shot_remote_engine.cc
+++ b/content/browser/speech/google_one_shot_remote_engine.cc
@@ -171,7 +171,10 @@ void GoogleOneShotRemoteEngine::StartRecognition() {
     net::URLRequestContext* request_context =
         url_context_->GetURLRequestContext();
     DCHECK(request_context);
-    std::string accepted_language_list = request_context->accept_language();
+    // TODO(pauljensen): GoogleOneShotRemoteEngine should be constructed with
+    // a reference to the HttpUserAgentSettings rather than accessing the
+    // accept language through the URLRequestContext.
+    std::string accepted_language_list = request_context->GetAcceptLanguage();
     size_t separator = accepted_language_list.find_first_of(",;");
     lang_param = accepted_language_list.substr(0, separator);
   }
diff --git a/content/browser/speech/google_streaming_remote_engine.cc b/content/browser/speech/google_streaming_remote_engine.cc
index 2f050bd..974118f 100644
--- a/content/browser/speech/google_streaming_remote_engine.cc
+++ b/content/browser/speech/google_streaming_remote_engine.cc
@@ -560,7 +560,10 @@ std::string GoogleStreamingRemoteEngine::GetAcceptedLanguages() const {
     net::URLRequestContext* request_context =
         url_context_->GetURLRequestContext();
     DCHECK(request_context);
-    std::string accepted_language_list = request_context->accept_language();
+    // TODO(pauljensen): GoogleStreamingRemoteEngine should be constructed with
+    // a reference to the HttpUserAgentSettings rather than accessing the
+    // accept language through the URLRequestContext.
+    std::string accepted_language_list = request_context->GetAcceptLanguage();
     size_t separator = accepted_language_list.find_first_of(",;");
     if (separator != std::string::npos)
       langs = accepted_language_list.substr(0, separator);
diff --git a/content/shell/shell_url_request_context_getter.cc b/content/shell/shell_url_request_context_getter.cc
index 9300dc6..3c4cb12 100644
--- a/content/shell/shell_url_request_context_getter.cc
+++ b/content/shell/shell_url_request_context_getter.cc
@@ -8,6 +8,7 @@
 #include "base/logging.h"
 #include "base/string_number_conversions.h"
 #include "base/string_split.h"
+#include "base/string_util.h"
 #include "base/threading/worker_pool.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/common/content_switches.h"
@@ -24,6 +25,7 @@
 #include "net/http/http_network_session.h"
 #include "net/http/http_server_properties_impl.h"
 #include "net/proxy/proxy_service.h"
+#include "net/url_request/static_http_user_agent_settings.h"
 #include "net/url_request/url_request_context.h"
 #include "net/url_request/url_request_context_storage.h"
 #include "net/url_request/url_request_job_factory_impl.h"
@@ -68,8 +70,9 @@ net::URLRequestContext* ShellURLRequestContextGetter::GetURLRequestContext() {
     storage_->set_server_bound_cert_service(new net::ServerBoundCertService(
         new net::DefaultServerBoundCertStore(NULL),
         base::WorkerPool::GetTaskRunner(true)));
-    url_request_context_->set_accept_language("en-us,en");
-    url_request_context_->set_accept_charset("iso-8859-1,*,utf-8");
+    storage_->set_http_user_agent_settings(
+        new net::StaticHttpUserAgentSettings(
+            "en-us,en", "iso-8859-1,*,utf-8", EmptyString()));
 
     scoped_ptr<net::HostResolver> host_resolver(
         net::HostResolver::CreateDefaultResolver(NULL));
diff --git a/net/net.gyp b/net/net.gyp
index ebab562..9603be5 100644
--- a/net/net.gyp
+++ b/net/net.gyp
@@ -819,6 +819,9 @@
         'url_request/fraudulent_certificate_reporter.h',
         'url_request/ftp_protocol_handler.cc',
         'url_request/ftp_protocol_handler.h',
+        'url_request/http_user_agent_settings.h',
+        'url_request/static_http_user_agent_settings.cc',
+        'url_request/static_http_user_agent_settings.h',
         'url_request/url_fetcher.cc',
         'url_request/url_fetcher.h',
         'url_request/url_fetcher_core.cc',
diff --git a/net/url_request/http_user_agent_settings.h b/net/url_request/http_user_agent_settings.h
new file mode 100644
index 0000000..84ae9fb
--- /dev/null
+++ b/net/url_request/http_user_agent_settings.h
@@ -0,0 +1,41 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef NET_URL_REQUEST_HTTP_USER_AGENT_SETTINGS_H_
+#define NET_URL_REQUEST_HTTP_USER_AGENT_SETTINGS_H_
+
+#include <string>
+
+#include "base/basictypes.h"
+#include "net/base/net_export.h"
+
+class GURL;
+
+namespace net {
+
+// The interface used by HTTP jobs to retrieve HTTP Accept-Language,
+// Accept-Charset and User-Agent header values.
+class NET_EXPORT HttpUserAgentSettings {
+ public:
+  HttpUserAgentSettings() {}
+  virtual ~HttpUserAgentSettings() {}
+
+  // Gets the value of 'Accept-Language' header field.
+  virtual std::string GetAcceptLanguage() const = 0;
+
+  // Gets the value of 'Accept-Charset' header field.
+  virtual std::string GetAcceptCharset() const = 0;
+
+  // Gets the UA string to use for the given URL.  Pass an empty URL to get
+  // the default UA string.
+  virtual std::string GetUserAgent(const GURL& url) const = 0;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(HttpUserAgentSettings);
+};
+
+}  // namespace net
+
+#endif  // NET_URL_REQUEST_HTTP_USER_AGENT_SETTINGS_H_
+
diff --git a/net/url_request/static_http_user_agent_settings.cc b/net/url_request/static_http_user_agent_settings.cc
new file mode 100644
index 0000000..475aa8f
--- /dev/null
+++ b/net/url_request/static_http_user_agent_settings.cc
@@ -0,0 +1,34 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "net/url_request/static_http_user_agent_settings.h"
+
+namespace net {
+
+StaticHttpUserAgentSettings::StaticHttpUserAgentSettings(
+    const std::string& accept_language,
+    const std::string& accept_charset,
+    const std::string& user_agent)
+    : accept_language_(accept_language),
+      accept_charset_(accept_charset),
+      user_agent_(user_agent) {
+}
+
+StaticHttpUserAgentSettings::~StaticHttpUserAgentSettings() {
+}
+
+std::string StaticHttpUserAgentSettings::GetAcceptLanguage() const {
+  return accept_language_;
+}
+
+std::string StaticHttpUserAgentSettings::GetAcceptCharset() const {
+  return accept_charset_;
+}
+
+std::string StaticHttpUserAgentSettings::GetUserAgent(const GURL& url) const {
+  return user_agent_;
+}
+
+}  // namespace net
+
diff --git a/net/url_request/static_http_user_agent_settings.h b/net/url_request/static_http_user_agent_settings.h
new file mode 100644
index 0000000..09cabd3
--- /dev/null
+++ b/net/url_request/static_http_user_agent_settings.h
@@ -0,0 +1,43 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef NET_URL_REQUEST_STATIC_HTTP_USER_AGENT_SETTINGS_H_
+#define NET_URL_REQUEST_STATIC_HTTP_USER_AGENT_SETTINGS_H_
+
+#include <string>
+
+#include "base/basictypes.h"
+#include "base/compiler_specific.h"
+#include "net/base/net_export.h"
+#include "net/url_request/http_user_agent_settings.h"
+
+namespace net {
+
+// An implementation of |HttpUserAgentSettings| that always provides the
+// same constant values for the HTTP Accept-Language, Accept-Charset, and
+// User-Agent headers.
+class NET_EXPORT StaticHttpUserAgentSettings : public HttpUserAgentSettings {
+ public:
+  StaticHttpUserAgentSettings(const std::string& accept_language,
+                              const std::string& accept_charset,
+                              const std::string& user_agent);
+  virtual ~StaticHttpUserAgentSettings();
+
+  // HttpUserAgentSettings implementation
+  virtual std::string GetAcceptLanguage() const OVERRIDE;
+  virtual std::string GetAcceptCharset() const OVERRIDE;
+  virtual std::string GetUserAgent(const GURL& url) const OVERRIDE;
+
+ private:
+  const std::string accept_language_;
+  const std::string accept_charset_;
+  const std::string user_agent_;
+
+  DISALLOW_COPY_AND_ASSIGN(StaticHttpUserAgentSettings);
+};
+
+}  // namespace net
+
+#endif  // NET_URL_REQUEST_STATIC_HTTP_USER_AGENT_SETTINGS_H_
+
diff --git a/net/url_request/url_request_context.cc b/net/url_request/url_request_context.cc
index 42a5789..94d7f22 100644
--- a/net/url_request/url_request_context.cc
+++ b/net/url_request/url_request_context.cc
@@ -12,6 +12,7 @@
 #include "net/cookies/cookie_store.h"
 #include "net/ftp/ftp_transaction_factory.h"
 #include "net/http/http_transaction_factory.h"
+#include "net/url_request/http_user_agent_settings.h"
 #include "net/url_request/url_request.h"
 
 namespace net {
@@ -26,6 +27,7 @@ URLRequestContext::URLRequestContext()
       proxy_service_(NULL),
       network_delegate_(NULL),
       http_server_properties_(NULL),
+      http_user_agent_settings_(NULL),
       transport_security_state_(NULL),
 #if !defined(DISABLE_FTP_SUPPORT)
       ftp_auth_cache_(new FtpAuthCache),
@@ -56,12 +58,11 @@ void URLRequestContext::CopyFrom(const URLRequestContext* other) {
   set_cookie_store(other->cookie_store_);
   set_transport_security_state(other->transport_security_state_);
   // FTPAuthCache is unique per context.
-  set_accept_language(other->accept_language_);
-  set_accept_charset(other->accept_charset_);
   set_http_transaction_factory(other->http_transaction_factory_);
   set_ftp_transaction_factory(other->ftp_transaction_factory_);
   set_job_factory(other->job_factory_);
   set_throttler_manager(other->throttler_manager_);
+  set_http_user_agent_settings(other->http_user_agent_settings_);
 }
 
 const HttpNetworkSession::Params* URLRequestContext::GetNetworkSessionParams(
@@ -84,8 +85,19 @@ void URLRequestContext::set_cookie_store(CookieStore* cookie_store) {
   cookie_store_ = cookie_store;
 }
 
-const std::string& URLRequestContext::GetUserAgent(const GURL& url) const {
-  return EmptyString();
+std::string URLRequestContext::GetAcceptCharset() const {
+  return http_user_agent_settings_ ?
+      http_user_agent_settings_->GetAcceptCharset() : EmptyString();
+}
+
+std::string URLRequestContext::GetAcceptLanguage() const {
+  return http_user_agent_settings_ ?
+      http_user_agent_settings_->GetAcceptLanguage() : EmptyString();
+}
+
+std::string URLRequestContext::GetUserAgent(const GURL& url) const {
+  return http_user_agent_settings_ ?
+      http_user_agent_settings_->GetUserAgent(url) : EmptyString();
 }
 
 void URLRequestContext::AssertNoURLRequests() const {
diff --git a/net/url_request/url_request_context.h b/net/url_request/url_request_context.h
index fb6af73..cbafc44 100644
--- a/net/url_request/url_request_context.h
+++ b/net/url_request/url_request_context.h
@@ -11,6 +11,7 @@
 #define NET_URL_REQUEST_URL_REQUEST_CONTEXT_H_
 
 #include <set>
+#include <string>
 
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
@@ -33,6 +34,7 @@ class FtpTransactionFactory;
 class HostResolver;
 class HttpAuthHandlerFactory;
 class HttpTransactionFactory;
+class HttpUserAgentSettings;
 class NetworkDelegate;
 class ServerBoundCertService;
 class ProxyService;
@@ -172,22 +174,18 @@ class NET_EXPORT URLRequestContext
 #endif
   }
 
+  // ---------------------------------------------------------------------------
+  // Legacy accessors that delegate to http_user_agent_settings_.
+  // TODO(pauljensen): Remove after all clients are updated to directly access
+  // http_user_agent_settings_.
   // Gets the value of 'Accept-Charset' header field.
-  const std::string& accept_charset() const { return accept_charset_; }
-  void set_accept_charset(const std::string& accept_charset) {
-    accept_charset_ = accept_charset;
-  }
-
+  std::string GetAcceptCharset() const;
   // Gets the value of 'Accept-Language' header field.
-  const std::string& accept_language() const { return accept_language_; }
-  void set_accept_language(const std::string& accept_language) {
-    accept_language_ = accept_language;
-  }
-
+  std::string GetAcceptLanguage() const;
   // Gets the UA string to use for the given URL.  Pass an invalid URL (such as
-  // GURL()) to get the default UA string.  Subclasses should override this
-  // method to provide a UA string.
-  virtual const std::string& GetUserAgent(const GURL& url) const;
+  // GURL()) to get the default UA string.
+  std::string GetUserAgent(const GURL& url) const;
+  // ---------------------------------------------------------------------------
 
   const URLRequestJobFactory* job_factory() const { return job_factory_; }
   void set_job_factory(const URLRequestJobFactory* job_factory) {
@@ -210,6 +208,16 @@ class NET_EXPORT URLRequestContext
 
   void AssertNoURLRequests() const;
 
+  // Get the underlying |HttpUserAgentSettings| implementation that provides
+  // the HTTP Accept-Language, Accept-Charset and User-Agent header values.
+  const HttpUserAgentSettings* http_user_agent_settings() const {
+    return http_user_agent_settings_;
+  }
+  void set_http_user_agent_settings(
+      HttpUserAgentSettings* http_user_agent_settings) {
+    http_user_agent_settings_ = http_user_agent_settings;
+  }
+
  private:
   // ---------------------------------------------------------------------------
   // Important: When adding any new members below, consider whether they need to
@@ -228,13 +236,12 @@ class NET_EXPORT URLRequestContext
   scoped_refptr<SSLConfigService> ssl_config_service_;
   NetworkDelegate* network_delegate_;
   HttpServerProperties* http_server_properties_;
+  HttpUserAgentSettings* http_user_agent_settings_;
   scoped_refptr<CookieStore> cookie_store_;
   TransportSecurityState* transport_security_state_;
 #if !defined(DISABLE_FTP_SUPPORT)
   scoped_ptr<FtpAuthCache> ftp_auth_cache_;
 #endif
-  std::string accept_language_;
-  std::string accept_charset_;
   // The charset of the referrer where this request comes from. It's not
   // used in communication with a server but is used to construct a suggested
   // filename for file download.
diff --git a/net/url_request/url_request_context_builder.cc b/net/url_request/url_request_context_builder.cc
index 217337f..f1cf1aa 100644
--- a/net/url_request/url_request_context_builder.cc
+++ b/net/url_request/url_request_context_builder.cc
@@ -9,6 +9,7 @@
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "base/logging.h"
+#include "base/string_util.h"
 #include "base/threading/thread.h"
 #include "base/thread_task_runner_handle.h"
 #include "net/base/cert_verifier.h"
@@ -25,6 +26,7 @@
 #include "net/http/http_network_session.h"
 #include "net/http/http_server_properties_impl.h"
 #include "net/proxy/proxy_service.h"
+#include "net/url_request/static_http_user_agent_settings.h"
 #include "net/url_request/url_request_context.h"
 #include "net/url_request/url_request_context_storage.h"
 
@@ -129,10 +131,6 @@ class BasicURLRequestContext : public URLRequestContext {
     return &storage_;
   }
 
-  void set_user_agent(const std::string& user_agent) {
-    user_agent_ = user_agent;
-  }
-
   void StartCacheThread() {
     cache_thread_.StartWithOptions(
         base::Thread::Options(MessageLoop::TYPE_IO, 0));
@@ -153,16 +151,10 @@ class BasicURLRequestContext : public URLRequestContext {
     return file_thread_.message_loop();
   }
 
-  virtual const std::string& GetUserAgent(
-      const GURL& /* url */) const OVERRIDE {
-    return user_agent_;
-  }
-
  protected:
   virtual ~BasicURLRequestContext() {}
 
  private:
-  std::string user_agent_;
   base::Thread cache_thread_;
   base::Thread file_thread_;
   URLRequestContextStorage storage_;
@@ -203,7 +195,8 @@ URLRequestContext* URLRequestContextBuilder::Build() {
   BasicURLRequestContext* context = new BasicURLRequestContext;
   URLRequestContextStorage* storage = context->storage();
 
-  context->set_user_agent(user_agent_);
+  storage->set_http_user_agent_settings(new StaticHttpUserAgentSettings(
+      accept_language_, accept_charset_, user_agent_));
 
   if (!network_delegate_)
     network_delegate_.reset(new BasicNetworkDelegate);
diff --git a/net/url_request/url_request_context_builder.h b/net/url_request/url_request_context_builder.h
index 66c8e7a..fd21f8a6 100644
--- a/net/url_request/url_request_context_builder.h
+++ b/net/url_request/url_request_context_builder.h
@@ -72,8 +72,15 @@ class NET_EXPORT URLRequestContextBuilder {
   void set_proxy_config_service(ProxyConfigService* proxy_config_service);
 #endif  // defined(OS_LINUX) || defined(OS_ANDROID)
 
-  // Call this function to specify a hard-coded User-Agent for all requests that
-  // don't have a User-Agent already set.
+  // Call these functions to specify hard-coded Accept-Language,
+  // Accept-Charset, or User-Agent header values for all requests that don't
+  // have the headers already set.
+  void set_accept_language(const std::string& accept_language) {
+    accept_language_ = accept_language;
+  }
+  void set_accept_charset(const std::string& accept_charset) {
+    accept_charset_ = accept_charset;
+  }
   void set_user_agent(const std::string& user_agent) {
     user_agent_ = user_agent;
   }
@@ -108,6 +115,8 @@ class NET_EXPORT URLRequestContextBuilder {
   URLRequestContext* Build();
 
  private:
+  std::string accept_language_;
+  std::string accept_charset_;
   std::string user_agent_;
   bool ftp_enabled_;
   bool http_cache_enabled_;
diff --git a/net/url_request/url_request_context_storage.cc b/net/url_request/url_request_context_storage.cc
index 12ea031..cc57078 100644
--- a/net/url_request/url_request_context_storage.cc
+++ b/net/url_request/url_request_context_storage.cc
@@ -17,6 +17,7 @@
 #include "net/http/http_transaction_factory.h"
 #include "net/proxy/proxy_service.h"
 #include "net/url_request/fraudulent_certificate_reporter.h"
+#include "net/url_request/http_user_agent_settings.h"
 #include "net/url_request/url_request_context.h"
 #include "net/url_request/url_request_job_factory.h"
 #include "net/url_request/url_request_throttler_manager.h"
@@ -123,4 +124,10 @@ void URLRequestContextStorage::set_throttler_manager(
   throttler_manager_.reset(throttler_manager);
 }
 
+void URLRequestContextStorage::set_http_user_agent_settings(
+    HttpUserAgentSettings* http_user_agent_settings) {
+  context_->set_http_user_agent_settings(http_user_agent_settings);
+  http_user_agent_settings_.reset(http_user_agent_settings);
+}
+
 }  // namespace net
diff --git a/net/url_request/url_request_context_storage.h b/net/url_request/url_request_context_storage.h
index bc040b2..62f4c2a 100644
--- a/net/url_request/url_request_context_storage.h
+++ b/net/url_request/url_request_context_storage.h
@@ -20,6 +20,7 @@ class HostResolver;
 class HttpAuthHandlerFactory;
 class HttpServerProperties;
 class HttpTransactionFactory;
+class HttpUserAgentSettings;
 class NetLog;
 class NetworkDelegate;
 class ServerBoundCertService;
@@ -65,6 +66,8 @@ class NET_EXPORT URLRequestContextStorage {
       FtpTransactionFactory* ftp_transaction_factory);
   void set_job_factory(URLRequestJobFactory* job_factory);
   void set_throttler_manager(URLRequestThrottlerManager* throttler_manager);
+  void set_http_user_agent_settings(
+      HttpUserAgentSettings* http_user_agent_settings);
 
  private:
   // We use a raw pointer to prevent reference cycles, since
@@ -84,6 +87,7 @@ class NET_EXPORT URLRequestContextStorage {
   scoped_refptr<SSLConfigService> ssl_config_service_;
   scoped_ptr<NetworkDelegate> network_delegate_;
   scoped_ptr<HttpServerProperties> http_server_properties_;
+  scoped_ptr<HttpUserAgentSettings> http_user_agent_settings_;
   scoped_refptr<CookieStore> cookie_store_;
   scoped_ptr<TransportSecurityState> transport_security_state_;
 
diff --git a/net/url_request/url_request_http_job.cc b/net/url_request/url_request_http_job.cc
index c65c33a..c011b436 100644
--- a/net/url_request/url_request_http_job.cc
+++ b/net/url_request/url_request_http_job.cc
@@ -39,6 +39,7 @@
 #include "net/http/http_transaction_factory.h"
 #include "net/http/http_util.h"
 #include "net/url_request/fraudulent_certificate_reporter.h"
+#include "net/url_request/http_user_agent_settings.h"
 #include "net/url_request/url_request.h"
 #include "net/url_request/url_request_context.h"
 #include "net/url_request/url_request_error_job.h"
@@ -211,12 +212,16 @@ URLRequestJob* URLRequestHttpJob::Factory(URLRequest* request,
   GURL redirect_url;
   if (request->GetHSTSRedirect(&redirect_url))
     return new URLRequestRedirectJob(request, network_delegate, redirect_url);
-  return new URLRequestHttpJob(request, network_delegate);
+  return new URLRequestHttpJob(request,
+                               network_delegate,
+                               request->context()->http_user_agent_settings());
 }
 
 
-URLRequestHttpJob::URLRequestHttpJob(URLRequest* request,
-                                     NetworkDelegate* network_delegate)
+URLRequestHttpJob::URLRequestHttpJob(
+    URLRequest* request,
+    NetworkDelegate* network_delegate,
+    const HttpUserAgentSettings* http_user_agent_settings)
     : URLRequestJob(request, network_delegate),
       response_info_(NULL),
       response_cookies_save_index_(0),
@@ -248,7 +253,8 @@ URLRequestHttpJob::URLRequestHttpJob(URLRequest* request,
           base::Bind(&URLRequestHttpJob::OnHeadersReceivedCallback,
                      base::Unretained(this)))),
       awaiting_callback_(false),
-      http_transaction_delegate_(new HttpTransactionDelegateImpl(request)) {
+      http_transaction_delegate_(new HttpTransactionDelegateImpl(request)),
+      http_user_agent_settings_(http_user_agent_settings) {
   URLRequestThrottlerManager* manager = request->context()->throttler_manager();
   if (manager)
     throttling_entry_ = manager->RegisterRequestUrl(request->url());
@@ -471,18 +477,22 @@ void URLRequestHttpJob::AddExtraHeaders() {
     }
   }
 
-  const URLRequestContext* context = request_->context();
-  // Only add default Accept-Language and Accept-Charset if the request
-  // didn't have them specified.
-  if (!context->accept_language().empty()) {
-    request_info_.extra_headers.SetHeaderIfMissing(
-        HttpRequestHeaders::kAcceptLanguage,
-        context->accept_language());
-  }
-  if (!context->accept_charset().empty()) {
-    request_info_.extra_headers.SetHeaderIfMissing(
-        HttpRequestHeaders::kAcceptCharset,
-        context->accept_charset());
+  if (http_user_agent_settings_) {
+    // Only add default Accept-Language and Accept-Charset if the request
+    // didn't have them specified.
+    std::string accept_language =
+        http_user_agent_settings_->GetAcceptLanguage();
+    if (!accept_language.empty()) {
+      request_info_.extra_headers.SetHeaderIfMissing(
+          HttpRequestHeaders::kAcceptLanguage,
+          accept_language);
+    }
+    std::string accept_charset = http_user_agent_settings_->GetAcceptCharset();
+    if (!accept_charset.empty()) {
+      request_info_.extra_headers.SetHeaderIfMissing(
+          HttpRequestHeaders::kAcceptCharset,
+          accept_charset);
+    }
   }
 }
 
@@ -921,7 +931,9 @@ void URLRequestHttpJob::Start() {
 
   request_info_.extra_headers.SetHeaderIfMissing(
       HttpRequestHeaders::kUserAgent,
-      request_->context()->GetUserAgent(request_->url()));
+      http_user_agent_settings_ ?
+          http_user_agent_settings_->GetUserAgent(request_->url()) :
+          EmptyString());
 
   AddExtraHeaders();
   AddCookieHeaderAndStart();
diff --git a/net/url_request/url_request_http_job.h b/net/url_request/url_request_http_job.h
index 3457166..ebfbe89 100644
--- a/net/url_request/url_request_http_job.h
+++ b/net/url_request/url_request_http_job.h
@@ -24,6 +24,7 @@ namespace net {
 class HttpResponseHeaders;
 class HttpResponseInfo;
 class HttpTransaction;
+class HttpUserAgentSettings;
 class URLRequestContext;
 
 // A URLRequestJob subclass that is built on top of HttpTransaction.  It
@@ -35,7 +36,9 @@ class URLRequestHttpJob : public URLRequestJob {
                                 const std::string& scheme);
 
  protected:
-  URLRequestHttpJob(URLRequest* request, NetworkDelegate* network_delegate);
+  URLRequestHttpJob(URLRequest* request,
+                    NetworkDelegate* network_delegate,
+                    const HttpUserAgentSettings* http_user_agent_settings);
 
   // Shadows URLRequestJob's version of this method so we can grab cookies.
   void NotifyHeadersComplete();
@@ -244,6 +247,8 @@ class URLRequestHttpJob : public URLRequestJob {
 
   scoped_ptr<HttpTransactionDelegateImpl> http_transaction_delegate_;
 
+  const HttpUserAgentSettings* http_user_agent_settings_;
+
   DISALLOW_COPY_AND_ASSIGN(URLRequestHttpJob);
 };
 
diff --git a/net/url_request/url_request_test_util.cc b/net/url_request/url_request_test_util.cc
index ae7d527..34335ae 100644
--- a/net/url_request/url_request_test_util.cc
+++ b/net/url_request/url_request_test_util.cc
@@ -16,6 +16,7 @@
 #include "net/base/server_bound_cert_service.h"
 #include "net/http/http_network_session.h"
 #include "net/http/http_server_properties_impl.h"
+#include "net/url_request/static_http_user_agent_settings.h"
 #include "net/url_request/url_request_job_factory_impl.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
@@ -113,10 +114,11 @@ void TestURLRequestContext::Init() {
             new net::DefaultServerBoundCertStore(NULL),
             base::WorkerPool::GetTaskRunner(true)));
   }
-  if (accept_language().empty())
-    set_accept_language("en-us,fr");
-  if (accept_charset().empty())
-    set_accept_charset("iso-8859-1,*,utf-8");
+  if (!http_user_agent_settings()) {
+    context_storage_.set_http_user_agent_settings(
+        new net::StaticHttpUserAgentSettings(
+            "en-us,fr", "iso-8859-1,*,utf-8", EmptyString()));
+  }
   if (!job_factory())
     context_storage_.set_job_factory(new net::URLRequestJobFactoryImpl);
 }
diff --git a/net/url_request/url_request_unittest.cc b/net/url_request/url_request_unittest.cc
index 181c509..2bf7f24 100644
--- a/net/url_request/url_request_unittest.cc
+++ b/net/url_request/url_request_unittest.cc
@@ -54,6 +54,7 @@
 #include "net/socket/ssl_client_socket.h"
 #include "net/test/test_server.h"
 #include "net/url_request/ftp_protocol_handler.h"
+#include "net/url_request/static_http_user_agent_settings.h"
 #include "net/url_request/url_request.h"
 #include "net/url_request/url_request_file_dir_job.h"
 #include "net/url_request/url_request_http_job.h"
@@ -3668,10 +3669,11 @@ TEST_F(URLRequestTestHTTP, InterceptPost307RedirectPost) {
 TEST_F(URLRequestTestHTTP, DefaultAcceptLanguage) {
   ASSERT_TRUE(test_server_.Start());
 
+  StaticHttpUserAgentSettings settings("en", EmptyString(), EmptyString());
   TestNetworkDelegate network_delegate;  // must outlive URLRequests
   TestURLRequestContext context(true);
   context.set_network_delegate(&network_delegate);
-  context.set_accept_language("en");
+  context.set_http_user_agent_settings(&settings);
   context.Init();
 
   TestDelegate d;
@@ -3686,13 +3688,15 @@ TEST_F(URLRequestTestHTTP, DefaultAcceptLanguage) {
 TEST_F(URLRequestTestHTTP, EmptyAcceptLanguage) {
   ASSERT_TRUE(test_server_.Start());
 
+  StaticHttpUserAgentSettings settings(
+      EmptyString(), EmptyString(), EmptyString());
   TestNetworkDelegate network_delegate;  // must outlive URLRequests
   TestURLRequestContext context(true);
   context.set_network_delegate(&network_delegate);
   context.Init();
   // We override the language after initialization because empty entries
   // get overridden by Init().
-  context.set_accept_language("");
+  context.set_http_user_agent_settings(&settings);
 
   TestDelegate d;
   URLRequest req(
@@ -3756,10 +3760,11 @@ TEST_F(URLRequestTestHTTP, OverrideAcceptEncoding) {
 TEST_F(URLRequestTestHTTP, DefaultAcceptCharset) {
   ASSERT_TRUE(test_server_.Start());
 
+  StaticHttpUserAgentSettings settings(EmptyString(), "en", EmptyString());
   TestNetworkDelegate network_delegate;  // must outlive URLRequests
   TestURLRequestContext context(true);
   context.set_network_delegate(&network_delegate);
-  context.set_accept_charset("en");
+  context.set_http_user_agent_settings(&settings);
   context.Init();
 
   TestDelegate d;
@@ -3775,13 +3780,15 @@ TEST_F(URLRequestTestHTTP, DefaultAcceptCharset) {
 TEST_F(URLRequestTestHTTP, EmptyAcceptCharset) {
   ASSERT_TRUE(test_server_.Start());
 
+  StaticHttpUserAgentSettings settings(
+      EmptyString(), EmptyString(), EmptyString());
   TestNetworkDelegate network_delegate;  // must outlive URLRequests
   TestURLRequestContext context(true);
   context.set_network_delegate(&network_delegate);
   context.Init();
   // We override the accepted charset after initialization because empty
   // entries get overridden otherwise.
-  context.set_accept_charset("");
+  context.set_http_user_agent_settings(&settings);
 
   TestDelegate d;
   URLRequest req(test_server_.GetURL("echoheader?Accept-Charset"),
@@ -3842,6 +3849,37 @@ TEST_F(URLRequestTestHTTP, OverrideUserAgent) {
   EXPECT_TRUE(StartsWithASCII(d.data_received(), "Lynx (textmode", true));
 }
 
+// Check that a NULL HttpUserAgentSettings causes the corresponding empty
+// User-Agent header to be sent but does not send the Accept-Language and
+// Accept-Charset headers.
+TEST_F(URLRequestTestHTTP, EmptyHttpUserAgentSettings) {
+  ASSERT_TRUE(test_server_.Start());
+
+  TestNetworkDelegate network_delegate;  // must outlive URLRequests
+  TestURLRequestContext context(true);
+  context.set_network_delegate(&network_delegate);
+  context.Init();
+  // We override the HttpUserAgentSettings after initialization because empty
+  // entries get overridden by Init().
+  context.set_http_user_agent_settings(NULL);
+
+  struct {
+    const char* request;
+    const char* expected_response;
+  } tests[] = { { "echoheader?Accept-Language", "None" },
+                { "echoheader?Accept-Charset", "None" },
+                { "echoheader?User-Agent", "" } };
+
+  for (size_t i = 0; i < ARRAYSIZE_UNSAFE(tests); i++) {
+    TestDelegate d;
+    URLRequest req(test_server_.GetURL(tests[i].request), &d, &context);
+    req.Start();
+    MessageLoop::current()->Run();
+    EXPECT_EQ(tests[i].expected_response, d.data_received())
+        << " Request = \"" << tests[i].request << "\"";
+  }
+}
+
 class HTTPSRequestTest : public testing::Test {
  public:
   HTTPSRequestTest() : default_context_(true) {
diff --git a/sync/internal_api/http_bridge.cc b/sync/internal_api/http_bridge.cc
index 96e1a58..5b38233 100644
--- a/sync/internal_api/http_bridge.cc
+++ b/sync/internal_api/http_bridge.cc
@@ -15,6 +15,7 @@
 #include "net/http/http_network_layer.h"
 #include "net/http/http_response_headers.h"
 #include "net/proxy/proxy_service.h"
+#include "net/url_request/static_http_user_agent_settings.h"
 #include "net/url_request/url_fetcher.h"
 #include "net/url_request/url_request_context.h"
 #include "net/url_request/url_request_status.h"
@@ -81,9 +82,8 @@ HttpBridge::RequestContext::RequestContext(
         network_task_runner,
     const std::string& user_agent)
     : baseline_context_(baseline_context),
-      network_task_runner_(network_task_runner),
-      user_agent_(user_agent) {
-  DCHECK(!user_agent_.empty());
+      network_task_runner_(network_task_runner) {
+  DCHECK(!user_agent.empty());
 
   // Create empty, in-memory cookie store.
   set_cookie_store(new net::CookieMonster(NULL, NULL));
@@ -109,8 +109,11 @@ HttpBridge::RequestContext::RequestContext(
   // should be tied to whatever the sync servers expect (if anything). These
   // fields should probably just be settable by sync backend; though we should
   // figure out if we need to give the user explicit control over policies etc.
-  set_accept_language(baseline_context->accept_language());
-  set_accept_charset(baseline_context->accept_charset());
+  http_user_agent_settings_.reset(new net::StaticHttpUserAgentSettings(
+      baseline_context->GetAcceptLanguage(),
+      baseline_context->GetAcceptCharset(),
+      user_agent));
+  set_http_user_agent_settings(http_user_agent_settings_.get());
 
   set_net_log(baseline_context->net_log());
 }
@@ -120,11 +123,6 @@ HttpBridge::RequestContext::~RequestContext() {
   delete http_transaction_factory();
 }
 
-const std::string& HttpBridge::RequestContext::GetUserAgent(
-    const GURL& url) const {
-  return user_agent_;
-}
-
 HttpBridge::URLFetchState::URLFetchState() : url_poster(NULL),
                                              aborted(false),
                                              request_completed(false),
diff --git a/sync/internal_api/public/http_bridge.h b/sync/internal_api/public/http_bridge.h
index 15001c2..40cf6e7 100644
--- a/sync/internal_api/public/http_bridge.h
+++ b/sync/internal_api/public/http_bridge.h
@@ -25,6 +25,7 @@ class HttpBridgeTest;
 
 namespace net {
 class HttpResponseHeaders;
+class HttpUserAgentSettings;
 class URLFetcher;
 }
 
@@ -58,12 +59,10 @@ class HttpBridge : public base::RefCountedThreadSafe<HttpBridge>,
     // The destructor MUST be called on the IO thread.
     virtual ~RequestContext();
 
-    virtual const std::string& GetUserAgent(const GURL& url) const OVERRIDE;
-
    private:
     net::URLRequestContext* const baseline_context_;
     const scoped_refptr<base::SingleThreadTaskRunner> network_task_runner_;
-    const std::string user_agent_;
+    scoped_ptr<net::HttpUserAgentSettings> http_user_agent_settings_;
 
     DISALLOW_COPY_AND_ASSIGN(RequestContext);
   };
diff --git a/webkit/tools/test_shell/test_shell_request_context.cc b/webkit/tools/test_shell/test_shell_request_context.cc
index 0ab9839..d15ea12 100644
--- a/webkit/tools/test_shell/test_shell_request_context.cc
+++ b/webkit/tools/test_shell/test_shell_request_context.cc
@@ -23,6 +23,7 @@
 #include "net/proxy/proxy_config_service.h"
 #include "net/proxy/proxy_config_service_fixed.h"
 #include "net/proxy/proxy_service.h"
+#include "net/url_request/http_user_agent_settings.h"
 #include "net/url_request/url_request_job_factory_impl.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebKit.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/platform/WebKitPlatformSupport.h"
@@ -34,6 +35,27 @@
 #include "webkit/tools/test_shell/simple_resource_loader_bridge.h"
 #include "webkit/user_agent/user_agent.h"
 
+class TestShellHttpUserAgentSettings : public net::HttpUserAgentSettings {
+ public:
+  TestShellHttpUserAgentSettings() {}
+  virtual ~TestShellHttpUserAgentSettings() {}
+
+  // hard-code A-L and A-C for test shells
+  virtual std::string GetAcceptLanguage() const OVERRIDE {
+    return "en-us,en";
+  }
+  virtual std::string GetAcceptCharset() const OVERRIDE {
+    return "iso-8859-1,*,utf-8";
+  }
+
+  virtual std::string GetUserAgent(const GURL& url) const OVERRIDE {
+    return webkit_glue::GetUserAgent(url);
+  }
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(TestShellHttpUserAgentSettings);
+};
+
 TestShellRequestContext::TestShellRequestContext()
     : ALLOW_THIS_IN_INITIALIZER_LIST(storage_(this)) {
   Init(FilePath(), net::HttpCache::NORMAL, false);
@@ -56,9 +78,7 @@ void TestShellRequestContext::Init(
       new net::DefaultServerBoundCertStore(NULL),
       base::WorkerPool::GetTaskRunner(true)));
 
-  // hard-code A-L and A-C for test shells
-  set_accept_language("en-us,en");
-  set_accept_charset("iso-8859-1,*,utf-8");
+  storage_.set_http_user_agent_settings(new TestShellHttpUserAgentSettings);
 
 #if defined(OS_POSIX) && !defined(OS_MACOSX)
   // Use no proxy to avoid ProxyConfigServiceLinux.
@@ -132,8 +152,3 @@ void TestShellRequestContext::Init(
 
 TestShellRequestContext::~TestShellRequestContext() {
 }
-
-const std::string& TestShellRequestContext::GetUserAgent(
-    const GURL& url) const {
-  return webkit_glue::GetUserAgent(url);
-}
diff --git a/webkit/tools/test_shell/test_shell_request_context.h b/webkit/tools/test_shell/test_shell_request_context.h
index 946248f..27ef6fe 100644
--- a/webkit/tools/test_shell/test_shell_request_context.h
+++ b/webkit/tools/test_shell/test_shell_request_context.h
@@ -34,8 +34,6 @@ class TestShellRequestContext : public net::URLRequestContext {
 
   virtual ~TestShellRequestContext();
 
-  virtual const std::string& GetUserAgent(const GURL& url) const OVERRIDE;
-
   webkit_blob::BlobStorageController* blob_storage_controller() const {
     return blob_storage_controller_.get();
   }